1. Field
The present invention relates generally to communication, and more specifically to techniques for selecting rates for data transmission in a communication system.
2. Background
In a communication system, a transmitter may transmit multiple streams of data via multiple transmission channels to a receiver. The transmission channels may be formed in the spatial domain, frequency domain, time domain, or a combination thereof. For example, the multiple transmission channels may correspond to different spatial channels in a multiple-input multiple-output (MIMO) communication system, different frequency subbands in an orthogonal frequency division multiplex (OFDM) communication system, or different time slots in a time division multiplex (TDM) communication system.
The transmission channels may experience different channel conditions (e.g., different fading, multipath, and interference effects) and may achieve different signal-to-noise ratios (SNRs). The SNR of a transmission channel determines its transmission capability, which is typically quantified by a particular data rate that may be reliably transmitted on the transmission channel. If the SNR varies from transmission channel to transmission channel, then the supported data rate would also vary from channel to channel. Furthermore, if the channel conditions vary with time, then the data rates supported by the transmission channels would also vary with time.
A major challenge in a coded communication system is selecting the appropriate rates to use for the multiple data streams based on the channel conditions. As used herein, a “rate” may indicate a particular data rate or information bit rate, a particular coding scheme, a particular modulation scheme, and so on to use for a data stream. The rate selection should maximize the overall throughput for the multiple transmission channels while meeting certain quality objectives, which may be quantified by a target packet error rate (PER).
There is therefore a need in the art for techniques to select suitable rates for data transmission on multiple transmission channels.